美国直管管道直径标准
美国标准直管和攻丝钻孔所示:
| 管道尺寸(英寸) | 每英寸螺纹数 | 管径(英寸) | 攻丝钻孔 |
| 1/8 | 27 | 0.405 | S |
| 1/4 | 18 | 0.540 | 29/64 |
| 3/8 | 18 | 0.675 | 19/32 |
| 1/2 | 14 | 0.840 | 47/64 |
| 3/4 | 14 | 1.050 | 15/16 |
| 1 | 11.5 | 1.315 | 1 3/16 |
| 1 1/4 | 11.5 | 1.660 | 1 33/64 |
| 1 1/2 | 11.5 | 1.900 | 1 3/4 |
| 2 | 11.5 | 2.375 | 2 7/32 |
| 2 1/2 | 8 | 2.875 | 2 21/32 |
| 3 | 8 | 3.500 | 3 9/32 |
| 3 1/2 | 8 | 4.000 | 3 25/32 |
| 4 | 8 | 4.500 | 4 9/32 |
| 4 1/2 | 8 | 5.000 | 4 25/32 |
| 5 | 8 | 5.563 | 5 11/32 |
| 6 | 8 | 6.625 | 6 13/32 |
